Credit or debit cards for starters are nothing short of shoppers' Novocain. Even in the age of digital purchases and virtual money we still attach a special value to dirty paper with pictures of presidents on it. Handing some of that to a cashier simply hurts more than handing over a little sliver of plastic.
Since it's based on my parents it's more emotionally close to me than some of my more surreal plays. And then I like the balance of the comic and the sad. It should play as funny but you should care about the characters and feel sad for them.